Abstract

In a psychological experiment the manipulation of independent variable is deliberatelyintroduced to observe its effects on the dependent variable. The cause-effect relationshipthen is infered. This article explained briefly two models of causal inferences. One modeldeveloped by Donald Campbell are more focused on design elements in ruling out threats tovalidity. On the other hand, Rubin’s model of causal inference emphasized in mathematicalprecision of the causal effects. The comparison of the two different but complementarymodels involves both randomized experiment and observational study.